Is this a bad heat treat?

G

Guy McVer

Joined
Mar 22, 2022
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I've got this old Gerber Vise. It's a poor quality competitor to the Squirt PS4. Garbage steel, garbage finish, garbage pliers, just all around garbage. The plain edge blade is crap and it usually comes with a crap edge on it.

So I go to sharpen the knife, and I notice a ding in the edge. Okay, fine. I'll just keep sharpening until it goes away. Hmm. Problem. It keeps coming back. Same spot, same ding. It keeps reappearing.

It isn't happening when I close the blade, so it's not blade rap. So I pinch that spot between my fingers and wiggle it back and forth. Huge ding appears. This only happens on that one spot. It's like the metal there is softer.

It has to be a bad heat treatment, right?

Right?

😕
 
I'd more likely suspect overheating during factory grinding of the edge. This happens quite a lot. And sometimes the damage goes pretty deep into an edge and requires a lot of subsequent resharpening to remove all that heat-damaged steel to sufficient depth, after which the edge becomes more stable. I've had a couple knives behaving like that and could actually see the steel at the apex roll or flatten under pressure from the edge of my thumbnail. And one blade on which the steel at the apex seemed to crumble to dust during light sharpening and couldn't form a crisp apex as a result. But again, that's usually something that can be fixed by sharpening away the damaged steel to adequate depth. Most times, two or three light resharpenings will take care of it. But some will take more time and patience.

Either way, the end result is a ruining of the temper of the edge. And in cheaper knives in particular, it's a pretty common phenomenon, to varying extent.

And if occurring in only one very narrow segment of an edge, I'd speculate it could also be issues with the quality of the steel itself, like impurities in the steel which affect how it responds to heat treat, regardless of whether the heat treat execution is good or bad.
 
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I agree such a small spot is most likely an impurity in the steel. Bad heat treat or overheating would effect a larger spot. All you can do is keep sharpening it until you get by the bad spot.
 
One thing you might do, to hopefully speed the resolution of the issue, is to first draw the edge perpendicularly across a coarse stone, as if cutting the stone in two. That's often an effective way to scrub off damaged/weakened steel quickly, after which you regrind new edge bevels in what is hopefully strong & stable steel. It's also a good way to straighten out any recurve issues, leaving the edge straighter in profile and setting a foudation for cleaner, better-looking bevels. It's obviously more work up front this way, rather than waiting over the course of several normal resharpenings to get it done. But if the damage is suspected to go to some significant depth, it's probably worthwhile to get it out of the way as quickly as possible and save some frustration over the longer run.
 
Well I finally managed to fix it, but boy did it take a long time! I almost gave up but then I noticed the "bad spot" was slowly shrinking, so I kept going until it finally disappeared completely.

So then I was going through some other old things today and I came across a pair of cheaply manufactured mini multi tool pliers with the exact same issue! o_O I'm starting to wonder if this isn't a common problem with the ultra low end stuff.
 
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